Ø Sampling Theory" Ø Fourier Analysis Ø Antialiasing Ø Supersampling Strategies" Ø The Hall illumination model. Ø Original ray tracing paper


 Preston Robertson
 10 months ago
 Views:
Transcription
1 CS 431/636 Advanced Rendering Techniques Ø Dr. David Breen Ø Korman 105D Ø Wednesday 6PM 8:50PM Presentation 6 5/16/12 Questions from ast Time? Ø Sampling Theory" Ø Fourier Analysis Ø Antialiasing Ø Supersampling Strategies" 1 2 Slide Credits Ø Charles B. Owen  Michigan State University Illumination and Shading Ø The Hall illumination model Hall, R. A. and Greenberg D.P., "A Testbed for Realistic Image Synthesis", IEEE Computer Graphics and Applications, 3(8, pp , ov Ø Original ray tracing paper Whitted, T., An Improved Illumination Model for Shaded Display, Communications of the ACM, 23(6, pp ( Discrete Illumination Models Ø What occurs when light strikes a surface is quite complex. Continuous process ight from infinite angle reflected in infinite directions Ø We are determining intensity of a pixel with Finite number of point lights Finite reflections into space Finite illumination directions Ø Hence, we must have a discrete model for lighting and illumination. Illumination Models Ø What should a lighting model entail? Discrete ights Types of surface reflection Ø Commercial systems can be quite complex Most start with a basic model and embellish to pick up details that are missing 5 6 1
2 Elements of ighting at a point Reflection Ø What we need is the amount of light reflected to the eye The surface normal ector to the light ector to the eye R Reflection direction R 7 8 This consists of several components Ø Diffuse reflection  light reflected in all directions equally (or close to equally. Most obects have a component of diffuse reflection other than pure specular reflection obects like mirrors. What determines the intensity of diffuse reflection? Characteristics Ø Since the intensity is the same in every direction, the only other characteristic is the angle between the light and the surface normal. The smaller this angle, the greater the diffuse reflection: 9 10 ambert s aw 11 w w w cos = w / w' w = w'cos Diffuse reflection decreases intensity by the cosine of the angle between the light and surface normal. Ø Specular reflection  If the light hits the surface and is reflected off mostly in a reflection direction, we have specular reflection. There is usually some diffusion. A perfect specular obect (no diffusion at all is a mirror. Most obects have some specular characteristics 12 2
3 Diffuse and Specular colors Where do these come from? Ø Typically Ø Most the colors reflected for diffuse and specular reflection are different surfaces tend to have: Deep color, the color of the paint, finish, interior material, etc. Diffuse Generally the surface appearance Specular The color of bright highlights, often more white then the surface color Diffuse Color Surface reflection characteristics, varnish, polish, smoothness Specular Color Components of the Hall Model The Hall Illumination Model I( = ksr Il ( Fsr (,"r, (cos" r, n + kst I l(fst (,"t, (cos" t, n' + kdr I l (Fdr (( $ + ksr Isr ( Fsr (,"R T r %sr + kst Ist (Fst (," T T t %st + kdr ( Fdr ( Ambient ight Hall Model Implementing Shadows Ø At every ray intersection shoot a shadow ray at every point light source in your scene Ø If an obect is hit before reaching the light, don t use the light when shading that intersection point Ø What if occluding obect is transparent? Make light s contribution weighted rather than binary
4 Ambient ight Ambient ight ( Ø Ambient light is light with no associated direction. The term in the Hall shading model for ambient light is: Ø is the coefficent of diffuse reflection. This term determines how much diffuse reflection a surface has. It ranges from 0 to 1 (as do most of these coefficients. 19 ( Ø (λ is the spectrum of the ambient light. It is a function of the light wavelength λ. In nature this is a continuous range. For us it is the intensity of three values: Red, Blue, and Green, since that is how we are representing our spectrum. In other words, there are only 3 possible values for λ. Simply perform this operation for each color 20 Ambient ight ( Implementation ( Ø F dr (λ is the Fresnell term for diffuse reflection. It specifies a curve of diffuse reflections for every value of the spectrum. We don t have every possible color, we only have three. So, this term specifies how much of each color will be reflected. It is simply the color of the obect. Ø It s common to combine and F dr (λ F dr (λ is really ust a color. Just call this is ambient surface color (λ is the ambient light color Ø Implementation (But you don t have to for(int c=0; c<3; c++ hallcolor[c] = lightambient[c] * * surfacediffuse[c]; of ight Sources Ø The iterator takes on the index of every light in the system.  coefficent of diffuse reflection. I l (λ  spectrum of light source. It is simply the color of the light. I l (( " of ight Sources I l (( " Ø component." is the surface normal at the point. is a vector towards the light. Dot product is the cosine of the angle (vectors must be normalized. alue decreases as the angle increases
5 of ight k Sources sr Ø k sr and I l (λ are now obvious. Ø F sr (λ,θ r, is the Fresnell term representing the specular reflection curve of the surface. Specular reflection is due to microfacets in the surface and this curve can be complex. In real world systems which strive for accuracy, this curve will be measured for a given material. ote that the curve is dependent on not only the wavelength, but also an angle. Ø A simplification of this is to ignore the angle, which is what we will do. But, the color of spectral highlights is independent of the color of the surface and is often ust white. 25 I l (," r, (cos" r, n The Spectral Intensity Function Ø (cosθ r, n is the spectral intensity function. It represents the cosine of the angle between the half reflection vector and the surface normal raised to a power. Maximum reflection is in the mirror direction 26 k sr I l (," r, (cos" r, n Cosine of Reflection Angle H k sr I l (," r, (cos" r, n Reflection Angles H This is an example α α of maximum reflection H cos r, = " H cos r, = " H + H = + In this case, the half vector is the same as the surface normal Cosine of angle between half vector and normal is 1. H bisects the angle between and Different Than Phong Shading H cos" r, = H Hall Model cos" r, = v r Phong Model Hall vs. Phong Specular Ø Same when = R cos(θ = cos(φ = 1 Ø Phong goes to zero when R. Then it goes negative Ø Hall only goes to zero when = &&. Ø Hall never negative. H R H
6 Highlight Coefficient Ø The term n is called the specular reflection highlight coefficient. Ø This effects how large the spectral highlight is. A larger value makes the highlight smaller and sharper. Matte surfaces has smaller n. 31 ery shiny surfaces have large n. A perfect mirror would have infinite n. from Other Surfaces Ø This is reflections of other surfaces Ø The only new terms are I sr (λ and T r Δsr The T r Δsr term reflects the fact that light falls off exponentially with distance. T r is a term which models how much light falls off per unit of travel within the medium. The Δsr term represents how far the light travels. ote that for mediums such as air and a small scene T r is close to 1, so you can sometimes ignore it. Glassner suggests 1/(1 + a*δsr instead 32 k sr I sr (," R T r sr The Reflection Direction Ø Given a view direction and a normal, the reflection direction R is: R = 2( " Ø I sr (λ is the color seen in the reflection direction, i.e. returned from the reflection ray Transmission Ø Transmission is light that passes through materials from ights Ø Bright spots from lights passing through obects. Most of the same issues apply. Ø I l (λ is the color of light. Ø F st (λ,θ t, specular transmissive color of obect Ø (cosθ t, n is how the specularity falls off if looking directly down the direction of transmission. 35 k st I l (F st (," t, (cos" t, n' Refractive Transmission Ø Given indices of refraction on above and below a surface, we can compute the angle for the view and transmission vectors using Snell s law 36 sin sin" " i = i θ i T  θ η i η 6
7 What Transmission ooks ike Index of Refraction Ø Ratio of speed of light in a vacuum to the speed of light in a substance T H H ' = " " 1, where " = 2 1 cos t, this time is (" H' η 1 and η 2 are the indices of refraction for the from and to obects respectively. 38 Substance Index acuum 1.0 Air Water 1.33 Glass 1.52 Diamond Sapphire 1.77 Salt 1.54 The Transmission Direction Total Internal Reflection " r = " i " T = " r 39 ( ( $ 1$" 2 r (1$ ( 2 $" r See Glassner p T η i η Ø If light is traveling from η i to a smaller η (e.g. out of water into air, the angle from the negative normal increases: 40 This can lead to the angle for T being >=90 degrees This is called total internal reflection Square root term in previous equation goes negative T T η i η Total Internal Reflection Hack What to do if square root is negative? Ø Return obect s reflective color, or Ø Shoot an internal reflective ray, or Ø Make T equal to  Ø Do the one that looks best 41 from Other Surfaces 42 k st I st (F st (," T T t st Ø This is transmitted light from other obects Ø K st  specular transmission coefficient Ø I st (λ is the light value from transmitted ray Ø F st (λ,θ Τ specular transmissive color of obect Ø T r Δst is the light fall off term, as before Glassner suggests 1/(1 + a*δst instead Ø Δst is distance traveled through obect 7
8 Hall Model Recap Hall Model Revisited I( = k sr I l (," r, (cos" r, n +k st I l (F st (," t, (cos" t, n' + I l (( $ +k sr I sr (," R T r %sr +k st I st (F st (," T T t %st + ( Ambient ight I( = k sr I l (," r, (cos" r, n +k st I l (F st (," t, (cos" t, n' + I l (( " sr +k r I sr (," R T r st +k st I st (F st (," T T t +k a ( Ambient ight ew Parameters Ø Adding two new coefficients in order to provide more flexibility to the model Ø K r Reflection coefficient If set to zero, the obect is not reflective This will allow you to generate Phongshaded models Ø K a Ambient coefficient Allows you to set ambient properties separate from diffuse properties 45 Algorithm Overview Ø For every primary ray that hits obect Shoot shadow ray at each light If you hit something don t use that light Or decrease light color if obect is transparent Calculate diffuse, specular and ambient colors Shoot reflected ray. Calculate color I sr (λ and add it to the shading equation Shoot transmitted ray. Calculate color I st (λ and add it to the shading equation Calculate transmissive specular highlight, if light ray goes through transparent obect 46 Generating trees for moderately complex scenes Ø Ø Ø Ø ight is reflected from several surfaces before reaching the viewer. The light ray behavior can be modeled as a tree. The shader traverses the tree, applying the shading equation at each node to calculate intensity. Tree should have a preset maximum depth Tricks Ø Terminate shadow ray ASAP Ø imit the depth of ray tree Ø Recursion can be stopped when color value drops below ε Ø Shooting a secondary ray can be tricky Move start point slightly away from surface Ø What if shadow ray hits a nonopaque obect? Ø What to do with total internal reflection and coming to the bottom of ray tree?
9 ext Programming Assignment Ø Update shading equation ew specular angle k d + k s = 1 Ø Add shadows Ø Add reflections I = k s I C s (cos n +k d I C d (cos" +k s I r C s +k a C d 49 9
Illumination & Shading
Illumination & Shading Goals Introduce the types of lightmaterial interactions Build a simple reflection modelthe Phong model that can be used with real time graphics hardware Why we need Illumination
More informationComp 410/510 Computer Graphics. Spring Shading
Comp 410/510 Computer Graphics Spring 2017 Shading Why we need shading Suppose we build a model of a sphere using many polygons and then color it using a fixed color. We get something like But we rather
More informationSo far, we have considered only local models of illumination; they only account for incident light coming directly from the light sources.
11 11.1 Basics So far, we have considered only local models of illumination; they only account for incident light coming directly from the light sources. Global models include incident light that arrives
More informationLecture 17: Recursive Ray Tracing. Where is the way where light dwelleth? Job 38:19
Lecture 17: Recursive Ray Tracing Where is the way where light dwelleth? Job 38:19 1. Raster Graphics Typical graphics terminals today are raster displays. A raster display renders a picture scan line
More informationRay Tracing. CSCI 420 Computer Graphics Lecture 15. Ray Casting Shadow Rays Reflection and Transmission [Ch ]
CSCI 420 Computer Graphics Lecture 15 Ray Tracing Ray Casting Shadow Rays Reflection and Transmission [Ch. 13.213.3] Jernej Barbic University of Southern California 1 Local Illumination Object illuminations
More informationTopic 9: Lighting & Reflection models 9/10/2016. Spot the differences. Terminology. Two Components of Illumination. Ambient Light Source
Topic 9: Lighting & Reflection models Lighting & reflection The Phong reflection model diffuse component ambient component specular component Spot the differences Terminology Illumination The transport
More informationCSE 681 Illumination and Phong Shading
CSE 681 Illumination and Phong Shading Physics tells us What is Light? We don t see objects, we see light reflected off of objects Light is a particle and a wave The frequency of light What is Color? Our
More informationPhotorealism: Ray Tracing
Photorealism: Ray Tracing Reading Assignment: Chapter 13 Local vs. Global Illumination Local Illumination depends on local object and light sources only Global Illumination at a point can depend on any
More informationComputer Graphics. Lecture 13. Global Illumination 1: Ray Tracing and Radiosity. Taku Komura
Computer Graphics Lecture 13 Global Illumination 1: Ray Tracing and Radiosity Taku Komura 1 Rendering techniques Can be classified as Local Illumination techniques Global Illumination techniques Local
More informationCENG 477 Introduction to Computer Graphics. Ray Tracing: Shading
CENG 477 Introduction to Computer Graphics Ray Tracing: Shading Last Week Until now we learned: How to create the primary rays from the given camera and image plane parameters How to intersect these rays
More informationCS 5625 Lec 2: Shading Models
CS 5625 Lec 2: Shading Models Kavita Bala Spring 2013 Shading Models Chapter 7 Next few weeks Textures Graphics Pipeline Light Emission To compute images What are the light sources? Light Propagation Fog/Clear?
More informationComputer Graphics. Lecture 10. Global Illumination 1: Ray Tracing and Radiosity. Taku Komura 12/03/15
Computer Graphics Lecture 10 Global Illumination 1: Ray Tracing and Radiosity Taku Komura 1 Rendering techniques Can be classified as Local Illumination techniques Global Illumination techniques Local
More informationComputer Graphics. Illumination and Shading
() Illumination and Shading Dr. Ayman Eldeib Lighting So given a 3D triangle and a 3D viewpoint, we can set the right pixels But what color should those pixels be? If we re attempting to create a realistic
More informationLighting affects appearance
Lighting affects appearance 1 Source emits photons Light And then some reach the eye/camera. Photons travel in a straight line When they hit an object they: bounce off in a new direction or are absorbed
More informationRecall: Basic Ray Tracer
1 Recall: Ray Tracing Generate an image by backwards tracing the path of light through pixels on an image plane Simulate the interaction of light with objects Recall: Basic Ray Tracer Trace a primary ray
More informationRaytracing CS148 AS3. Due :59pm PDT
Raytracing CS148 AS3 Due 20100725 11:59pm PDT We start our exploration of Rendering  the process of converting a highlevel objectbased description of scene into an image. We will do this by building
More informationReview for Raytracing Algorithm and Hardware
Review for Raytracing Algorithm and Hardware Reporter: 邱敬捷博士候選人 LanDa Van ( 范倫達 ), Ph. D. Department of Computer Science National Chiao Tung University Taiwan, R.O.C. Summer, 2017 1 2017/7/26 Outline
More informationCPSC 314 LIGHTING AND SHADING
CPSC 314 LIGHTING AND SHADING UGRAD.CS.UBC.CA/~CS314 slide credits: Mikhail Bessmeltsev et al 1 THE RENDERING PIPELINE Vertices and attributes Vertex Shader Modelview transform Pervertex attributes Vertex
More informationComputer Graphics. Shading. Based on slides by Dianna Xu, Bryn Mawr College
Computer Graphics Shading Based on slides by Dianna Xu, Bryn Mawr College Image Synthesis and Shading Perception of 3D Objects Displays almost always 2 dimensional. Depth cues needed to restore the third
More informationCS5620 Intro to Computer Graphics
So Far wireframe hidden surfaces Next step 1 2 Light! Need to understand: How lighting works Types of lights Types of surfaces How shading works Shading algorithms What s Missing? Lighting vs. Shading
More informationAnnouncements. Written Assignment 2 out (due March 8) Computer Graphics
Announcements Written Assignment 2 out (due March 8) 1 Advanced Ray Tracing (Recursive) Ray Tracing Antialiasing Motion Blur Distribution Ray Tracing Ray Tracing and Radiosity Assumptions Simple shading
More informationLets assume each object has a defined colour. Hence our illumination model is looks unrealistic.
Shading Models There are two main types of rendering that we cover, polygon rendering ray tracing Polygon rendering is used to apply illumination models to polygons, whereas ray tracing applies to arbitrary
More informationChapter 32 Light: Reflection and Refraction. Copyright 2009 Pearson Education, Inc.
Chapter 32 Light: Reflection and Refraction Units of Chapter 32 The Ray Model of Light Reflection; Image Formation by a Plane Mirror Formation of Images by Spherical Mirrors Index of Refraction Refraction:
More informationLecture 7 Notes: 07 / 11. Reflection and refraction
Lecture 7 Notes: 07 / 11 Reflection and refraction When an electromagnetic wave, such as light, encounters the surface of a medium, some of it is reflected off the surface, while some crosses the boundary
More informationLight. Form of Electromagnetic Energy Only part of Electromagnetic Spectrum that we can really see
Light Form of Electromagnetic Energy Only part of Electromagnetic Spectrum that we can really see Facts About Light The speed of light, c, is constant in a vacuum. Light can be: REFLECTED ABSORBED REFRACTED
More informationCOMP environment mapping Mar. 12, r = 2n(n v) v
Rendering mirror surfaces The next texture mapping method assumes we have a mirror surface, or at least a reflectance function that contains a mirror component. Examples might be a car window or hood,
More informationLecture 4: Reflection Models
Lecture 4: Reflection Models CS 660, Spring 009 Kavita Bala Computer Science Cornell University Outline Light sources Light source characteristics Types of sources Light reflection Physicsbased models
More informationCMSC427 Shading Intro. Credit: slides from Dr. Zwicker
CMSC427 Shading Intro Credit: slides from Dr. Zwicker 2 Today Shading Introduction Radiometry & BRDFs Local shading models Light sources Shading strategies Shading Compute interaction of light with surfaces
More informationRay Tracing. CS334 Fall Daniel G. Aliaga Department of Computer Science Purdue University
Ray Tracing CS334 Fall 2013 Daniel G. Aliaga Department of Computer Science Purdue University Ray Casting and Ray Tracing Ray Casting Arthur Appel, started around 1968 Ray Tracing Turner Whitted, started
More informationIllumination & Shading I
CS 543: Computer Graphics Illumination & Shading I Robert W. Lindeman Associate Professor Interactive Media & Game Development Department of Computer Science Worcester Polytechnic Institute gogo@wpi.edu
More informationOrthogonal Projection Matrices. Angel and Shreiner: Interactive Computer Graphics 7E AddisonWesley 2015
Orthogonal Projection Matrices 1 Objectives Derive the projection matrices used for standard orthogonal projections Introduce oblique projections Introduce projection normalization 2 Normalization Rather
More informationspecular diffuse reflection.
Lesson 8 Light and Optics The Nature of Light Properties of Light: Reflection Refraction Interference Diffraction Polarization Dispersion and Prisms Total Internal Reflection Huygens s Principle The Nature
More informationCS Illumination and Shading. Slide 1
CS 112  Illumination and Shading Slide 1 Illumination/Lighting Interaction between light and surfaces Physics of optics and thermal radiation Very complex: Light bounces off several surface before reaching
More informationCSE 167: Lecture #7: Color and Shading. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2011
CSE 167: Introduction to Computer Graphics Lecture #7: Color and Shading Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2011 Announcements Homework project #3 due this Friday,
More informationECS 175 COMPUTER GRAPHICS. Ken Joy.! Winter 2014
ECS 175 COMPUTER GRAPHICS Ken Joy Winter 2014 Shading To be able to model shading, we simplify Uniform Media no scattering of light Opaque Objects No Interreflection Point Light Sources RGB Color (eliminating
More informationIndirect Illumination
Indirect Illumination Michael Kazhdan (601.457/657) HB Ch. 14.1, 14.2 FvDFH 16.1, 16.2 Surface Illumination Calculation Multiple light source: 2 Viewer N 1 V I = I E + K A I A + K D N, + K S V, R n I Overview
More informationRecap: Refraction. Amount of bending depends on:  angle of incidence  refractive index of medium. (n 2 > n 1 ) n 2
Amount of bending depends on:  angle of incidence  refractive index of medium Recap: Refraction λ 1 (n 2 > n 1 ) Snell s Law: When light passes from one transparent medium to another, the rays will be
More informationPHY 112: Light, Color and Vision. Lecture 11. Prof. Clark McGrew Physics D 134. Review for Exam. Lecture 11 PHY 112 Lecture 1
PHY 112: Light, Color and Vision Lecture 11 Prof. Clark McGrew Physics D 134 Review for Exam Lecture 11 PHY 112 Lecture 1 From Last Time Lenses Ray tracing a Convex Lens Announcements The midterm is Thursday
More informationDeferred Rendering Due: Wednesday November 15 at 10pm
CMSC 23700 Autumn 2017 Introduction to Computer Graphics Project 4 November 2, 2017 Deferred Rendering Due: Wednesday November 15 at 10pm 1 Summary This assignment uses the same application architecture
More informationComputer Graphics I. Assignment 3
UNIVERSITÄT DES SAARLANDES Dr.Ing. Hendrik P.A. Lensch Max Planck Institut Informatik Art Tevs (tevs@mpiinf.mpg.de) Boris Ajdin (bajdin@mpiinf.mpg.de) Matthias Hullin (hullin@mpiinf.mpg.de) 12. November
More informationColor and Light. CSCI 4229/5229 Computer Graphics Summer 2008
Color and Light CSCI 4229/5229 Computer Graphics Summer 2008 Solar Spectrum Human Trichromatic Color Perception Are A and B the same? Color perception is relative Transmission,Absorption&Reflection Light
More informationReflection and Refraction
Reflection and Refraction Lecture #22 Tuesday, ovember 19, 2013 (Major Updates 12/06/13) How about Interreflections ote reflections Granite tabletop Visible on base Also on handle This is a featured picture
More informationSAMPLING AND NOISE. Increasing the number of samples per pixel gives an antialiased image which better represents the actual scene.
SAMPLING AND NOISE When generating an image, Mantra must determine a color value for each pixel by examining the scene behind the image plane. Mantra achieves this by sending out a number of rays from
More informationRaycast Rendering Maya 2013
2000 2012 Michael O'Rourke Raycast Rendering Maya 2013 (See also the Intro to Lights and Rendering tutorial for an introduction to the basics of rendering an image) Concept There are several algorithms
More informationThreeDimensional Graphics V. Guoying Zhao 1 / 55
Computer Graphics ThreeDimensional Graphics V Guoying Zhao 1 / 55 Shading Guoying Zhao 2 / 55 Objectives Learn to shade objects so their images appear threedimensional Introduce the types of lightmaterial
More informationLighting and Shading. Slides: Tamar Shinar, Victor Zordon
Lighting and Shading Slides: Tamar Shinar, Victor Zordon Why we need shading Suppose we build a model of a sphere using many polygons and color each the same color. We get something like But we want 2
More informationIllumination and Shading
Illumination and Shading Illumination (Lighting)! Model the interaction of light with surface points to determine their final color and brightness! The illumination can be computed either at vertices or
More informationTurn on the Lights: Reflectance
Turn on the Lights: Reflectance Part 2: Shading Tuesday, October 15 2012 Lecture #14 Goal of Shading Model simple light sources Point light sources Extended light sources Ambient lighting Model lighting
More information03 RENDERING PART TWO
03 RENDERING PART TWO WHAT WE HAVE SO FAR: GEOMETRY AFTER TRANSFORMATION AND SOME BASIC CLIPPING / CULLING TEXTURES AND MAPPING MATERIAL VISUALLY DISTINGUISHES 2 OBJECTS WITH IDENTICAL GEOMETRY FOR NOW,
More informationComputergrafik. Matthias Zwicker Universität Bern Herbst 2016
Computergrafik Matthias Zwicker Universität Bern Herbst 2016 Today More shading Environment maps Reflection mapping Irradiance environment maps Ambient occlusion Reflection and refraction Toon shading
More informationLecture 14: Refraction
Lecture 14: Refraction We know from experience that there are several transparent substances through which light can travel air, water, and glass are three examples When light passes from one such medium
More informationComputer Graphics Lecture 11
1 / 14 Computer Graphics Lecture 11 Dr. Marc Eduard Frîncu West University of Timisoara May 15th 2012 2 / 14 Outline 1 Introduction 2 Transparency 3 Reflection 4 Recap 3 / 14 Introduction light = local
More informationCEng 477 Introduction to Computer Graphics Fall
Illumination Models and SurfaceRendering Methods CEng 477 Introduction to Computer Graphics Fall 2007 2008 Illumination Models and Surface Rendering Methods In order to achieve realism in computer generated
More informationIntroduction to Computer Graphics. Farhana Bandukwala, PhD Lecture 14: Light Interacting with Surfaces
Introduction to Computer Graphics Farhana Bandukwala, PhD Lecture 14: Light Interacting with Surfaces Outline Computational tools Reflection models Polygon shading Computation tools Surface normals Vector
More informationIllumination Models and SurfaceRendering Methods. Chapter 10
Illumination Models and SurfaceRendering Methods Chapter 10 Illumination and Surface Rendering Given scene specifications object positions, optical properties of the surface, viewer position, viewing
More informationChapter 26 Geometrical Optics
Chapter 26 Geometrical Optics 26.1 The Reflection of Light 26.2 Forming Images With a Plane Mirror 26.3 Spherical Mirrors 26.4 Ray Tracing and the Mirror Equation 26.5 The Refraction of Light 26.6 Ray
More informationIllumination and Shading
Illumination and Shading Computer Graphics COMP 770 (236) Spring 2007 Instructor: Brandon Lloyd 2/14/07 1 From last time Texture mapping overview notation wrapping Perspectivecorrect interpolation Texture
More informationAssignment 6: Ray Tracing
Assignment 6: Ray Tracing Programming Lab Due: Monday, April 20 (midnight) 1 Introduction Throughout this semester you have written code that manipulated shapes and cameras to prepare a scene for rendering.
More informationShading, lighting, & BRDF Theory. Cliff Lindsay, PHD
Shading, lighting, & BRDF Theory Cliff Lindsay, PHD Overview of today s lecture BRDF Characteristics Lights in terms of BRDFs Classes of BRDFs Ambient light & Shadows in terms of BRDFs Decomposing Reflection
More informationMaterials & Shadows. Steve Rotenberg CSE168: Rendering Algorithms UCSD, Winter 2017
Materials & Shadows Steve Rotenberg CSE168: Rendering Algorithms UCSD, Winter 2017 Diffuse Surfaces In an earlier lecture, we discussed diffuse surfaces We looked at the idealized Lambertian diffuse case
More informationReflections and Refractions in Ray Tracing
Reflections and Refractions in Ray Tracing Bram de Greve (bram.degreve@gmail.com) 10th October 2004 When you re writing a ray tracer, soon or late you ll stumble on the problem of reflection and refraction.
More informationShading & Material Appearance
Shading & Material Appearance ACM. All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/help/faqfairuse/. MIT EECS 6.837 Matusik
More informationWhy we need shading?
Why we need shading? Suppose we build a model of a sphere using many polygons and color it with glcolor. We get something like But we want Lightmaterial interactions cause each point to have a different
More informationWhat is it? How does it work? How do we use it?
What is it? How does it work? How do we use it? Dual Nature http://www.youtube.com/watch?v=dfpeprq7ogc o Electromagnetic Waves display wave behavior o Created by oscillating electric and magnetic fields
More informationGlobal Illumination. COMP 575/770 Spring 2013
Global Illumination COMP 575/770 Spring 2013 Final Exam and Projects COMP 575 Final Exam Friday, May 3 4:00 pm COMP 770 (and 575 extra credit) Projects Final report due by end of day, May 1 Presentations:
More informationLighting and Shading Computer Graphics I Lecture 7. Light Sources Phong Illumination Model Normal Vectors [Angel, Ch
15462 Computer Graphics I Lecture 7 Lighting and Shading February 12, 2002 Frank Pfenning Carnegie Mellon University http://www.cs.cmu.edu/~fp/courses/graphics/ Light Sources Phong Illumination Model
More informationOptics: Reflection and Refraction (approx. completion time: 2.5 h) (3/28/11)
Optics: Reflection and Refraction (approx. completion time: 2.5 h) (3/28/11) Introduction In this lab you will investigate the reflection and refraction of light. Reflection of light from a surface is
More informationLIGHT. Descartes particle theory, however, could not be used to explain diffraction of light.
1 LIGHT Theories of Light In the 17 th century Descartes, a French scientist, formulated two opposing theories to explain the nature of light. These two theories are the particle theory and the wave theory.
More informationReflection and Refraction of Light
PC1222 Fundamentals of Physics II Reflection and Refraction of Light 1 Objectives Investigate for reflection of rays from a plane surface, the dependence of the angle of reflection on the angle of incidence.
More informationLighting affects appearance
Lighting affects appearance 1 Source emits photons Light And then some reach the eye/camera. Photons travel in a straight line When they hit an object they: bounce off in a new direction or are absorbed
More informationUniversity Physics 227N/232N Chapters 3032: Optics Homework Optics 1 Due This Friday at Class Time Quiz This Friday
University Physics 227N/232N Chapters 3032: Optics Homework Optics 1 Due This Friday at Class Time Quiz This Friday Dr. Todd Satogata (ODU/Jefferson Lab) satogata@jlab.org http://www.toddsatogata.net/2014odu
More information4.5 Images Formed by the Refraction of Light
Figure 89: Practical structure of an optical fibre. Absorption in the glass tube leads to a gradual decrease in light intensity. For optical fibres, the glass used for the core has minimum absorption at
More informationRendering Light Reflection Models
Rendering Light Reflection Models Visual Imaging in the Electronic Age Donald P. Greenberg October 3, 2017 Lecture #13 Program of Computer Graphics, Cornell University General Electric  167 Cornell in
More information13. Brewster angle measurement
13. Brewster angle measurement Brewster angle measurement Objective: 1. Verification of Malus law 2. Measurement of reflection coefficient of a glass plate for p and s polarizations 3. Determination
More information(Equation 24.1: Index of refraction) We can make sense of what happens in Figure 24.1
241 Refraction To understand what happens when light passes from one medium to another, we again use a model that involves rays and wave fronts, as we did with reflection. Let s begin by creating a short
More informationShading and Illumination
Shading and Illumination OpenGL Shading Without Shading With Shading Physics Bidirectional Reflectance Distribution Function (BRDF) f r (ω i,ω ) = dl(ω ) L(ω i )cosθ i dω i = dl(ω ) L(ω i )( ω i n)dω
More informationLight: Geometric Optics
Light: Geometric Optics The Ray Model of Light Light very often travels in straight lines. We represent light using rays, which are straight lines emanating from an object. This is an idealization, but
More informationLessons Learned from HW4. Shading. Objectives. Why we need shading. Shading. Scattering
Lessons Learned from HW Shading CS Interactive Computer Graphics Prof. David E. Breen Department of Computer Science Only have an idle() function if something is animated Set idle function to NULL, when
More information12:402:40 3:004:00 PM
Physics 294H l Professor: Joey Huston l email:huston@msu.edu l office: BPS3230 l Homework will be with Mastering Physics (and an average of 1 handwritten problem per week) Helproom hours: 12:402:40
More informationOptics: Laser Light Show Student Advanced Version
Optics: Laser Light Show Student Advanced Version In this lab, you will explore the behavior of light. You will observe reflection and refraction of a laser beam in jello, and use a diffraction pattern
More informationUNIT C: LIGHT AND OPTICAL SYSTEMS
1 UNIT C: LIGHT AND OPTICAL SYSTEMS Science 8 2 LIGHT BEHAVES IN PREDICTABLE WAYS. Section 2.0 1 3 LIGHT TRAVELS IN RAYS AND INTERACTS WITH MATERIALS Topic 2.1 RAY DIAGRAMS Scientists use ray diagrams
More informationCS452/552; EE465/505. Lighting & Shading
CS452/552; EE465/505 Lighting & Shading 217 15 Outline! More on Lighting and Shading Read: Angel Chapter 6 Lab2: due tonight use ASDW to move a 2D shape around; 1 to center Local Illumination! Approximate
More informationRay Optics. Ray model Reflection Refraction, total internal reflection Color dispersion Lenses Image formation Magnification Spherical mirrors
Ray Optics Ray model Reflection Refraction, total internal reflection Color dispersion Lenses Image formation Magnification Spherical mirrors 1 Ray optics Optical imaging and color in medicine Integral
More informationRefraction of Light. c = m / s. n = c v. The index of refraction is never less than 1. Some common indices of refraction are listed below.
Refraction of Light The speed of light in a vacuum is c = 3.00 10 8 m / s In air, the speed is only slightly less. In other transparent materials, such as glass and water, the speed is always less than
More informationRadiometry & BRDFs CS295, Spring 2017 Shuang Zhao
Radiometry & BRDFs CS295, Spring 2017 Shuang Zhao Computer Science Department University of California, Irvine CS295, Spring 2017 Shuang Zhao 1 Today s Lecture Radiometry Physics of light BRDFs How materials
More informationEXPERIMENT 8 PFUND REFRACTION
EXPERIMENT 8 PFUND REFRACTION A narrow beam of light passes through the face of a glass plate, then undergoes a diffuse reflection from the rear surface of the plate. The diffused light travels back toward
More informationObjectives Shading in OpenGL. Front and Back Faces. OpenGL shading. Introduce the OpenGL shading methods. Discuss polygonal shading
Objectives Shading in OpenGL Introduce the OpenGL shading methods  per vertex shading vs per fragment shading  Where to carry out Discuss polygonal shading  Flat  Smooth  Gouraud CITS3003 Graphics
More informationObjectives. Shading II. Distance Terms. The Phong Reflection Model
Shading II Objectives Introduce distance terms to the shading model. More details about the Phong model (lightmaterial interaction). Introduce the Blinn lighting model (also known as the modified Phong
More informationL. R. & S. M. VISSANJI ACADEMY SECONDARY SECTION PHYSICS  GRADE: VIII REFRACTION OF LIGHT
L. R. & S. M. VISSANJI ACADEMY SECONDARY SECTION  201617 PHYSICS  GRADE: VIII REFRACTION OF LIGHT REFRACTION When light travels from one transparent medium to another transparent medium, it bends from
More informationAP* Optics Free Response Questions
AP* Optics Free Response Questions 1978 Q5 MIRRORS An object 6 centimeters high is placed 30 centimeters from a concave mirror of focal length 10 centimeters as shown above. (a) On the diagram above, locate
More informationLight: Geometric Optics
Light: Geometric Optics 23.1 The Ray Model of Light Light very often travels in straight lines. We represent light using rays, which are straight lines emanating from an object. This is an idealization,
More informationsurface: reflectance transparency, opacity, translucency orientation illumination: location intensity wavelength pointsource, diffuse source
walters@buffalo.edu CSE 480/580 Lecture 18 Slide 1 Illumination and Shading Light reflected from nonluminous objects depends on: surface: reflectance transparency, opacity, translucency orientation illumination:
More informationComputer Graphics 1. Chapter 7 (June 17th, 2010, 24pm): Shading and rendering. LMU München Medieninformatik Andreas Butz Computergraphik 1 SS2010
Computer Graphics 1 Chapter 7 (June 17th, 2010, 24pm): Shading and rendering 1 The 3D rendering pipeline (our version for this class) 3D models in model coordinates 3D models in world coordinates 2D Polygons
More informationPY106 Class31. Index of refraction. Refraction. Index of refraction. Sample values of n. Rays and wavefronts. index of refraction: n v.
Refraction Index of refraction When an EM wave travels in a vacuum, its speed is: c = 3.00 x 10 8 m/s. In any other medium, light generally travels at a slower speed. The speed of light v in a material
More informationName Section Date. Experiment Reflection and Refraction
Name Section Date Introduction: Experiment Reflection and Refraction The travel of light is often represented in geometric optics by a light ray, a line that is drawn to represent the straightline movement
More informationMore on POVRay Surface Shading Surface color
More on POVRay Surface Shading Once an object is defined, we need to deal with other issues such as Surface color pigment Surface properties finish Surface color Pigment statement The color or pattern
More informationRaycasting. Ronald Peikert SciVis Raycasting 31
Raycasting Ronald Peikert SciVis 2007  Raycasting 31 Direct volume rendering Volume rendering (sometimes called direct volume rendering) stands for methods that generate images directly from 3D scalar
More informationSurface Reflection Models
Surface Reflection Models Frank Losasso (flosasso@nvidia.com) Introduction One of the fundamental topics in lighting is how the light interacts with the environment. The academic community has researched
More informationLight II. Physics 2415 Lecture 32. Michael Fowler, UVa
Light II Physics 2415 Lecture 32 Michael Fowler, UVa Today s Topics Huygens principle and refraction Snell s law and applications Dispersion Total internal reflection Huygens Principle Newton s contemporary
More informationFINDING THE INDEX OF REFRACTION  WebAssign
Name: Book: Period: Due Date: Lab Partners: FINDING THE INDEX OF REFRACTION  WebAssign Purpose: The theme in this lab is the interaction between light and matter. Matter and light seem very different
More information